[AArch64] Add missing Neon Types (#126945)
The AAPCS64 adds a number of vector types to the C unconditionally:
https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#11appendix-support-for-advanced-simd-extensions
The equivalent SVE types are already available in clang:
https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#12appendix-support-for-scalable-vectors
__mfp8 is defined in the ACLE
https://arm-software.github.io/acle/main/acle.html#data-types
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Co-authored-by: David Green <david.green@arm.com>
